Study On The Key Technologies Of Novel Rf Components Of Nonlinear Electromagnetic Metamaterials

Electromagnetic metamaterial?EMM?is a kind of artificial material.When the unit cell of EMM is much smaller than the working wavelength,it can be considered as homogeneous medium.EMM exhibits many novel electromagnetic properties and has important potential applications,and has attracted wide research attention.However,there are many un-solved problems and bottle-necks,including the large loss,narrow bandwidth,and un-tunable frequency band.The active tunable EMMs and nonlinear metamaterials?NMMs?have shown novel advantages for solving the issues appeared in conventional EMMs.Therefore,this thesis investigates the composing mechanisms and design methods of tunable dual-band EMMs and NMMs,and explores several applications,including metamaterial absorbers?MMAs?,EMM based microwave passive components,and chip-scale low phase noise oscillator and accelerometer based on the air-slot line-defected photonic crystal?PhC?optomechanical cavity.The research details and contributions are shown as follows.1.The effective permeability and its shift mechanism of ferrite under different dc magnetic fields are firstly analyzed by using electromagnetic wave theory.The composing mechanism of dual-band tunable EMM and THz single-band EMM are investigated.Then three kinds of tunable dual-band EMMs composed of ferrite and three conventional EMM structures,including SRR-Wire structure,?-shaped structure,and shorted wire structure,and the THz EMM are designed and the corresponding transmission/reflection,effective media properties,tunability of the working bandwidth are investigated.Such kind of ferrite based tunable metamaterials exhibit the tuning rate up to 2.85 MHz/Oe,and the obtained maximum tuning range can reach to 23%.2.By using electrodynamics theory,static-magnetic theory,and nonlinear coupling theory,the nonlinear coupling mechanism and controlling rule between electromagnetic induced force and mechanical/elastic force in a kind of magnetostrictive NMM are investigated.The numerical simulation and experimental demonstration methods are analyzed,the resonant frequency of such magnetostrictive NMM and the controllable NMM based on the magnetorheological fluid are analyzed and investigated.3.Based on the rectangular waveguide measurement method,several tunable MMAs,including snow-flake resonator structure,ferrite inspired structure,and dielectric covered conventional structure are designed and achieved.By using electromagnetic theory,numerical simulation,and experimental demonstration,the absorbing strength and absorbing mode,controllability of absorbing frequency under different magnetic fields and dielectric covered distance/thicknesses are investigated.Those tunable MMAs exhibit frequency tuning ranges up to 20%.4.By using coupling mechanism and numerical simulation,the inductive coupling and magnetic coupling mechanisms and effects of two asymmetric SRR resonators are analyzed,and then a novel compact bandpass filter based on such asymmetric resonators is investigated and achieved.Based on the obtained filter unit,the diplexer and triplexer are designed.The frequency selectivity and filtering performances of these components are investigated by numerical simulation and experimental demonstration.These compact components have comparable return loss,inert loss,and out-of-band rejection,port isolation performances for the conventional microwave components.5.By using optomechanical coupling theory,a low phase noised optomechanical oscillator?OMO?based on the air-slot line-defected PhC nano cavity and integrated with Ge-detector is designed.The fabrication method,measurement setup for characterizing the optical and mechanical modes are analyzed.The mechanisms for the subharmonics and harmonics,threshold for optomechanical oscillation are investigated.The phase noise of OMO are experimentally demonstrated as well.Moreover,the interaction between the self-pulsation oscillation and optomechanical oscillation within the silicon optomechanical nano cavity and the frequency synchronization are observed and analyzed.The designed OMO has phase noise of-125 d Bc/Hz at offset of 10 kHz and harmonics up to 6.9 GHz,and can achieve the 1/2,1/3,1/4 subharmonics.6.By using optomechanical coupling theory,the displacement mechanism and effect of optomechanical membrane under external force are investigated,and a chip-scale optomechanical accelerometer based on the large mass PhC nano cavity is designed.The frequency instability,sensitivity,resolution of such optomechanical accelerometer are demonstrated,and the corresponding theoretical noise limit are analyzed.The acceleration sensitivity of 625 ?g/Hz and resolution of 8.2 ?g/?Hz?^1/2 are achieved,and 1/6 subharmonics and more than 100 harmonics are obtained as well.In conclusions,this thesis has obtained several frequency-controllable and tunable EMMs,MMAs,NMMs,and EMM based microwave passive components,and also obtained the chip-scale low-phase OMO integrated with Ge-detector,and chip-scale optomechanical accelerometer.The achievements in this thesis can be widely used in many areas of such as microwave/millimeter waves/THz system,thermal radiometer,electromagnetic shielding/compatibility,magnetic field and pressure sensing,RF frequency reference/clocking,inertial navigation system,etc.